Question

Match the following columns and select the correct option:

	Column-I		Column-II
(a)	Dragonflies	(i)	Biocontrol agents of several plant pathogens
(b)	Bacillus thuringiensis	(ii)	Get rid of aphids and mosquitoes
(c)	Glomus	(iii)	Narrow spectrum insecticidal applications
(d)	Baculoviruses	(iv)	Biocontrol agents of lepidopteran plant pests
		(v)	Absorb phosphorus from soil

• A. (a)-(iii), (b)-(v), (c)-(iv), (d)-(i)
• B. (a)-(ii), (b)-(i), (c)-(iii), (d)-(iv)
• C. (a)-(ii), (b)-(iii), (c)-(iv), (d)-(v)
• D. (a)-(ii), (b)-(iv), (c)-(v), (d)-(iii)

Answer 1

The correct option is D (a)-(ii), (b)-(iv), (c)-(v), (d)-(iii)

Biocontrol is the method of controlling pests that relies on natural predation rather than introduced chemicals. It greatly reduces our dependence on toxic chemicals and pesticides.

• Dragonflies are used to get rid of mosquitoes. They are natural predators for mosquitoes.
• The bacterium Bacillus thuringiensis (Bt) is a microbial biocontrol agent used to control lepidopteran pests (tobacco budworm, armyworm). These are available in sachets as dried spores which are mixed with water and sprayed onto vulnerable plants such as Brassica and fruit trees, where these are eaten by the insect larvae. In the gut of the larvae, the toxin is released and the larvae get killed.
• Nucleopolyhedrovirus is a genus belonging to baculoviruses. They are pathogens of insects and other arthropods. They are used as biological control agents for species-specific, narrow spectrum insecticidal applications.

Biofertilisers enrich the nutrient quality of the soil. Glomus is a fungus which forms symbiotic associations with the roots of higher plants. The association is known as mycorrhiza. The fungal symbiont in such associations helps the plants in absorbing phosphorus from soil.